Field of the Invention
The present invention relates in general to the field of information handling system wireless communication, and more particularly to information handling system proximity sensing.
Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Portable information handling systems process information with processing components disposed in a portable housing. One type of portable housing is a laptop or convertible information handling system that integrates a display and keyboard in rotationally coupled housing portions. For example, the housing portions rotate relative to each other to open positions that exposed the keyboard and display for interaction with an end user. Another type of portable housing is planar housing that contains processing components in a flat space that is covered by a display. Examples of such planar housings are smartphone and tablet devices that generally accept end user inputs through a touchscreen display. Due to their small physical size, portable information handling systems often interface with external peripheral devices that accept and present information with a more user friendly footprint, such as external mechanical keyboards to accept keyed inputs and external display devices to present visual images in sizes that are greater than that available with an integrated display. In some instances, portable information handling systems have cabled communication with external peripheral devices, such as USB cables. Often, however, portable housings have limited room to include ports for external cables so that wireless communication is used to interface with external peripherals, such as IEEE 802.11 WiFi interfaces or Bluetooth interfaces.
Generally, portable information handlings are used on-the-go and include features targeted towards mobile users, such as simple web browsing and email interfaces. Smartphones in planar housings (and many tablets) include wireless wide area networking (WWAN) resources to interact with cellular telephone service provider networks. Advantageously, WWAN access allows end users to receive email and perform basic networking tasks, such as web surfing, in most locations where cellular service provides telephone access. If WiFi is available, such as through wireless local area network (WLAN) hotspot or other resources, portable information handling systems can select WLAN service over WWAN service in order to minimize wireless communication costs. As a result, at various times a portable information handling system may have multiple radios sending and receiving information through multiple antennae simultaneously. In addition, shorter range and lower bandwidth communications may be used, such as Bluetooth or near field communications (NFC) interfaces.
One difficulty with operating multiple radios at a portable information handling system is that government Specific Absorption Rate (SAR) regulations limit the amount of radiation emitted by radios located in close proximity to an end user. When radio power is reduced to meet SAR requirements, end user experience can be impacted, such as with lower data rates, greater error rates, and reduced service ranges. One way to increase radio transmission power is to detect the proximity of the end user and turn power down. Proximity detection provides an improved end user experience by supporting greater radio transmission power if a portable information handling system is not located proximate to an end user. Typically, a capacitive proximity sensor that detects changes in electrostatic charge is located proximate the transmitting antenna so that the radio can turn power down if an object is detected within a distance of the antenna that could lead to excessive radiation if the object is a human body part, such as the head. Although proximity sensors detect the presence of a human form near an antenna, proximity sensors generally do not distinguish between human forms and other objects. Thus, for example, when a portable information handling system rests on a desktop, its radio transmission power is reduced even though no human form is nearby that would absorb the radiation.